content: /*
   * Copyright 2011-2016 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package ix;
  
  import java.util.*;
  
  final class IxUnion<T> extends IxSource<T, T> {
  
      final Iterable<? extends T> other;
  
      IxUnion(Iterable<T> source, Iterable<? extends T> other) {
          super(source);
          this.other = other;
      }
  
      @Override
      public Iterator<T> iterator() {
          return new UnionIterator<T>(source.iterator(), other.iterator());
      }
  
      static final class UnionIterator<T> extends IxSourceIterator<T, T> {
  
          final Iterator<? extends T> other;
  
          final Set<T> set;
  
          boolean second;
  
          UnionIterator(Iterator<T> it, Iterator<? extends T> other) {
              super(it);
              this.other = other;
              this.set = new HashSet<T>();
          }
  
          @Override
          protected boolean moveNext() {
              Set<T> set = this.set;
              for (;;) {
                  if (second) {
                      Iterator<? extends T> other = this.other;
                      while (other.hasNext()) {
                          T v = other.next();
                          if (set.add(v)) {
                              value = v;
                              hasValue = true;
                              return true;
                          }
                      }
  
                      done = true;
                      return false;
                  }
  
                  Iterator<T> it = this.it;
                  while (it.hasNext()) {
                      T v = it.next();
                      if (set.add(v)) {
                          value = v;
                          hasValue = true;
                          return true;
                      }
                  }
  
                  second = true;
              }
          }
      }
  }
  